Method of manufacturing conductor terminals



Sept. 15, 1942. D. HOPPENSTAND 2,295,899

METHOD OF MANUFACTURING CONDUCTOR TERMINALS Filed April 19, 1940 Fig.1. Fig. 2. i 5'.

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METHOD OF'MANUFACTUBING GONDUCTOR TEBMIN David Hoppenstand, Fox Chapel, r... Application April 19, 1940, SerlalNo. 330,562

. 1 Claim. (cue-15555) This invention relates to a novel method of manufacturing a conductor terminal and, speciflcally, to a terminal having provision for attachment to the end of a conductor such as a cable, andmeans wherebythe terminal maybe secured to a switchboard paneL'bus-bar, or the. like. Numerous forms of conductor terminals have been proposed heretofore. All of them, however, so. faras I am aware, have been characterized by numerous objectionable features. .In the first place, most terminals are composed of' several parts and considerable difllculty is involved in the assembly thereof. Special tools are required in some cases. The cost of such terminals is relatively high because of their complex construction. A further defect common to all known terminalsis that when they are tightened on V the conductor, the movable portion of the terniinal, such as a threaded sleeve, moves away from the end of the insulation remaining on the cable, thereby leaving a bare length of cable which has to be covered as by taping.

I have invented a novel method for-the manufacture of a conductor terminal whereby the aforementioned objections to previous terminals are overcome. In a preferred embodiment, the terminal of my invention comprises a split sleeve having. a tapered, threaded end. A'connecting lug is formed integral with the sleeve and a nut is disposed on an unthreaded portion of the sleeve intermediate the threaded end andthe lug. The method'I have invented for the manufacture of such terminal comprises threading the tubular end of a blank such as a casting, turning .35 down the intermediate portion, threading a .nut on the latter, slotting the threaded end, and then forming a taper thereon in a manner to be explained in detail hereinafter.

Fora complete understanding of the terminal of 'my invention and my method for the manufacture thereof, reference is made to the accom- 1 panying drawing illustrating a preferred embodiment and the successive stages of its manufacture. In the drawing:

Fig. 1 is a central sectional view through a terminal blank on a plane perpendicular to that of a the connecting lug;

Fig. 2 is an end view such as would be seen on looking toward the tubular end of the blank of Fig. 1:

Figs. 3 through 8 are views similar to Fig. ,1 showing successive stages in the manufacture of the terminal;

Fig. 9 is a view similar to Fig. 1 showing a 55 completed terminal therein;

' terminal blank ll comprises a tubular portion ll having a longitudinal bore l2 therethrough and anintegral lug II having a hole ll therethrough to receive a securing screw or bolt. The blank it may conveniently be acasting' composed of copper or other suitable conducting metal or alloy.

The first stepin the manufacture of the finished terminal is illustrated in Fig. 3 and comprises simplv the threading of the end of the tubular portion ll of the blank III, as indicated at It. After the tubular end of the blank has been threaded, the intermediate. portion thereof is turned down to the diameter indicated by the dotted lines l6, thafresult of this operation be- ,ing illustrated in 4. The blank is thus provided with an intermediate portion of reduced tion I! of the tubular end of the blank is such that the nut I9 is relatively loose thereon.

The next operation is the spreading of the slotted, threaded end of -the blank as indicated in Fig. 7. This spreading may be accomplished by any suitable means such as the driving of a tapered plug into the threaded end of the ter-' minal. When the slotted end of the blank has been spread as shown in Fig. 7, the bore I2 is enlarged to the diameter indicated by the dotted end of the blank. The diameter indicated bythe dotted lines 20 is chosen to accommodate a given size of cable and it will be apparent that when such cable is inserted'into the tubular end with a cable end I inserted of the blank and the nut l9 turned up on the threaded end of the blank, the segmental portions of the latter will be contracted and caused to grip the cable at a point spaced from the end thereof.

The final operation in the manufacture of the terminal is the formation of annular grooves 2| on the interior of the threaded end thereof. These grooves are'deflned by annular surfaces perpendicular to the axis of the bore and frusatoconical surfaces forming sharp-edged, tooth-like projections which serve very effectively to prevent withdrawal of a conductor when the segmental portions of the threaded end of the terminal have been contracted thereabout.

Fig. 9 illustrates a conductor such as a cable 22 having an external layer of insulation 23 thereon, the insulation being removed from the end of the cable and the latter inserted into the bore through the tubular portion of a finished terminal 24 until the insulation left on the conductor abuts against the threaded end of the terminal. As previously indicated, the segmental portions of the threaded end'of -the terminal may be contracted and caused to grip the conductor tightly, by turning the nut is outwardly along the threaded end of the terminal. 7

Fig. illustrates the relation of the parts when the nut l9 has'been turned home. As there shown, the segmental portions of the threaded end of the terminal have been contracted into tight gripping engagement with the conductor and the teeth formed by the grooves 2| have been caused to bite into the surfaces of the wires forming the cable.

It is to be particularlynoted that the end of the terminal, when positioned on a conductor, abuts the end of the insulation 23, thereby mak ing it unnecessary to apply any supplemental insulating covering such as tape or the like. A

further feature of novelty is that the terminal grips the conductor at a point spaced from the end of the latter, instead of at the extremity thereof, as do the terminals known heretofore, thereby exerting a much stronger grip thereon in opposition to forces tending to pull the cable out of the terminal.

Fig. 11 illustrates a modification which is similar in all respects to that described above except that it is formed from a blank 25 stamped from tubular stock. Terminals of various types have been so formed heretofore and no further detailed explanation of the method of forming the blank is necessary. As will be apparent, the steps in the manufacture of the terminal shown in Fig. 11 are the same as those for the manufacture of the finished terminal 24.

It will be apparent from the foregoing description that my invention is characterized by numerous advantages over terminals and methads for the manufacture thereof known heretofore. In the first place, my terminal is capable of exerting such a powerful grip on a cable that pull-out of the latter is practically impossible. This results from a the fact that the tapered segments at the threaded end of the terminal grip the cable at a point spaced from the extreme end of the latter, as well as the fact that the edges of the grooves 2| bit into the cable conductors themselves. A further advantage has already been mentioned, the fact that the terminal abuts the end of the insulation left on the conductor. The terminal is relatively simple in construction and can be manufactured at relatively low cost since the several operations may be conducted in a turret lathe with a single chucking. A further advantage is the fact that the terminal comprises only two parts and these are permanently assembled in manufacture. This greatly facilitates use of the terminal in the field since each one is complete in itself and t is not necessary to assemble parts from different containers with the possibility that certain parts will be missing or exhausted. The terminal may be attached, furthermore, with an ordinary wrench and requires no special tools. The setting-up is a very simple operation and involves no particular skill.

A further important advantage of the invention is that the tapered segments exert a constant outward force on the nut. tending to prevent loosening thereof under vibration or the like. Thesegments, furthermore, may be contracted sufliciently to exert gripping engagement on conductors several sizes smaller than the bore 20 so it is not necessary to provide a different terminal for each cable size.

Although I have illustrated and described but a preferred embodiment and practice of the invention with a modification of the former, it

I thereof, turning a nut onto the blank suiilciently with a longitudinal taper inwardly by reason to leave the segments between slots projecting beyond the nut, spreading the projecting ends of the segments sufficiently to deform them beyond the elastic limit and impart to their exterior surface a flare toward said end, and boring the blank axially to a uniform inside diam eter for at least a substantial portion of the length of said segments inwardly from the outer ends thereof, thereby providing the segments of the flaring of the exterior thereof.

DAVID HOPPENSTAND. 

